Phase Behavior of Rigid Objects on a Cubic Lattice

Grand canonical Monte Carlo simulations were carried out to examine phase transitions of rigid lattice objects. The objects studied are coarse representations of planar, spherical, cubic, and cylindrical shapes on a simple cubic lattice. Multihistogram reweighting methods were used to generate the phase diagrams; critical points were determined using finite-size scaling methods. Spheres and capped cylinders exhibit a first-order transition from fluid to crystalline phases in the athermal limit. Small cubes and planar structures show continuous order-disorder transitions. For a six-armed cross object, there is evidence of a metastable vapor-liquid-phase transition lying within the fluid-solid-phase envelope.